Carbon filtering involves activated carbon for removing contaminants and impurities from water by chemical adsorption. Carbon granules have a pore structure and surface area that is conducive to exposure to active sites within the carbon. Filtration using activated carbon works by a process called adsorption whereby contaminants in a fluid become trapped inside the pore structure of carbon granules. Carbon filtering is commonly used for water purification, air purification and industrial gas processing. When used for water purification, active carbon, also referred to as activated charcoal, is most effective at removing chlorine, sediment and volatile organic compounds; and is less effective at removing minerals, salts and dissolved inorganic compounds.
Particles commonly removed by activated charcoal filters range from 0.5 to 50 micrometers in diameter. The efficacy of an activated charcoal is affected by the rate of flow through the charcoal particulate. The slower the rate at which water flows through a bed of charcoal particulate, the greater the rate of exposure of contaminants to filter media. Saturating a filter media also continues to allow exposure and adsorption of contaminants to filter media. Contaminants do not release back into a fluid once adsorbed by a carbon media unless heated above 100° C.
Activated charcoal provides an environment for microbes in soil that are beneficial to living plants. Since contaminants are not released from activated charcoal in ambient temperatures they tend to remain attached to the activated charcoal and not release into soil when used in compost.
Home use filters often use disposable filter cartridges that contain activated charcoal in a convenient container that allows water to flow through without allowing charcoal fragments to fall out of the container.
Plastic disposable items add to the waste stream and take a considerable time to break down. Even broken down, many plastics are toxic to the environment. Reusable plastic products, or products made from materials that occur naturally in the environment, reduce the size and toxicity of the waste stream.